I installed lower spring rate KW springs on KW V3

Ive had Kw V3 on my 2007 speed3 for maybe 8 years. The rear struts have been in for rebuilding once in that time.

I am pretty sick of the harsh ride around town so I called KW and they told me they had 2 options for softer springs for the kit.

The KW V3 kits come with Front 400.05 LBS./in. Rear 192 LBS./in.

They don't sell anything softer for the rear only for the front.

The softest front springs they sell are 280 LBS./in for (Part # 60110046). $80 each plus shipping. They also sell a 340 LBS./in spring which is only 60 LBS./in softer. Thhey took a month to arrived from Germany.

I installed them along with new dust covers because the old ones were in pieces. BAD design by KW. The cover smashes down into the strut and breaks apart. WTF? $8 each but as we know its installation that is annoying not so much the $16.

Ive only driven maybe 100 miles but honestly this is what should have come with this kit from the beginning. 400 lbs/in is way too harsh.

I would say it feels like maybe 20% softer. Impact harshness is definitely reduced. I need to play with the rebound and compression adjustments now and get an alignment. The car was sitting lower so I had to raise it an inch with these softer springs to get the same wheel gap and no rubbing.

Here is old and new side by side. You can see its a thinner coil. You reuse the helper spring.

 

Those dust boots will always fail. Get something like these if you want to protect your investment. I got a different brand on my Miata (Inertia Lab), but they should all function the same to keep direct water/dirt out and away from the shock piston.

https://www.riactionusa.com/store-1/p/coilover-sleeves-set-of-2

 

Wow thanks for the tip!

I've lived with these lower rate springs and honestly, I think they are too soft...the front struts bottom out much too easily. Then again these struts are 8 years old. I just sent them in to KW for a rebuild. They are also squeaking over moderate size bumps very loudly.

At least I think they are the cause of the squeak. Both control arm bushings and sway bar bushings are new so I don't know what else it could be other than the strut.

Im hoping the strut rebuild prevents the bottoming out from being so common. If not its the spring rate plus having the car lowered.Will advise after I get the struts back from KW.

 

When running softer rates, you usually need to run longer springs to prevent bottoming out/coil bind. You can try a smaller bump stop thickness, but I don't recommend that because it can cause premature failure of the piston/seals if you hit a really bad bump. Plus, that shit is gonna hurt too (less cushion for the pushin)

 

Ya well...Im stuck with what I got. For now.

I sent my struts in for repair and they dynoed fine but the seals were dry and squeaking like mad so they changed them free-o-charge. 2 week turn around.

They have a 340 LBS./in spring which is likely a better fit for the struts. 400 too stiff, 280 is too soft for so little suspension travel.

I wonder if raising the car will help at all with bottoming out.

 

I raised the car, added +8 (of 12) compression and +6 rebound to the KWs and did some extensive driving over the holidays. This thing bottoms out like crazy. I cant do this anymore. Its scary. I dont even know why they would sell those springs. The car is too heavy up front for 280 lbs/inch.

I gotta go to 340 or ditch these KWs and find another brand of coil overs.